From: Konrad Dybcio <konrad.dybcio@oss.qualcomm.com>
To: ferreira@se-rg.io, Bjorn Andersson <andersson@kernel.org>,
Konrad Dybcio <konradybcio@kernel.org>,
Abel Vesa <abelvesa@kernel.org>, Rob Herring <robh@kernel.org>,
Krzysztof Kozlowski <krzk+dt@kernel.org>,
Conor Dooley <conor+dt@kernel.org>
Cc: linux-arm-msm@vger.kernel.org, devicetree@vger.kernel.org,
linux-kernel@vger.kernel.org,
Georg Gottleuber <ggo@tuxedocomputers.com>,
Ettore Chimenti <ek5.chimenti@gmail.com>,
Jens Glathe <jens.glathe@oldschoolsolutions.biz>,
Srinivas Kandagatla <srini@kernel.org>
Subject: Re: [PATCH v2] arm64: dts: qcom: x1e80100-medion-sprchrgd-14-s1: Add PWM backlight
Date: Mon, 26 Oct 2026 11:00:14 +0100 [thread overview]
Message-ID: <0a36d49a-a1c8-4434-a9c9-36cb1ccfc097@oss.qualcomm.com> (raw)
In-Reply-To: <20261025-medion-sprchrgd-14-backlight-v2-1-bf2979485ec2@se-rg.io>
On 10/25/26 8:51 AM, Sérgio Ferreira via B4 Relay wrote:
> From: Sérgio Ferreira <ferreira@se-rg.io>
>
> The eDP panel (CSOT MNE007ZA3-2, IPS LCD) cannot have its brightness
> set over eDP AUX. With no backlight phandle on the panel, panel-edp
> falls back to the DP AUX backlight, which registers dp_aux_backlight
> with a maximum brightness of 0, so brightness control has no effect.
>
> Brightness is driven by PWM instead. UEFI leaves PM8550 LPG channel 3
> running and the PWM output configured on PM8550 GPIO 8, and drives
> PMC8380_3 GPIO 4 high as the backlight enable:
>
> pm8550 gpio8 : out low func1 vin-0 no pull push-pull medium
> pmc8380_3 gpio4 : out high normal vin-1 pull-down push-pull medium
>
> The panel configuration in the Windows ACPI tables confirmed this.
> (PMIC-controlled PWM, PMIC 1, bank 3, 9-bit, 2 kHz).
>
> Describe this with a pwm-backlight node: enable pm8550_pwm, add pinctrl
> states for the enable GPIO and for gpio8 func1, and attach the
> backlight to the panel.
>
> Tested on a Medion SPRCHRGD 14 S1 (X1E78100): brightness control over
> the full range, brightness keys, suspend/resume and restore after
> reboot.
>
> Assisted-by: LLM
> Signed-off-by: Sérgio Ferreira <ferreira@se-rg.io>
> ---
Reviewed-by: Konrad Dybcio <konrad.dybcio@oss.qualcomm.com>
Konrad
next prev parent reply other threads:[~2026-10-26 10:00 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-10-25 7:51 Sérgio Ferreira via B4 Relay
2026-10-26 10:00 ` Konrad Dybcio [this message]
2026-10-26 17:08 ` Ettore Chimenti
2026-10-26 18:26 ` Sérgio Ferreira
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